BY TOO many accounts, one of the most horrible sounds a skier can hear on a ski slope is the popping noise of the anterior cruciate ligament (ACL) as it tears during a fall. That sound, which usually heralds a painful, debilitating, and expensive knee injury, is heard no less by the most accomplished skiers than by the clumsiest novices.
Severe knee sprains are now the most common medically significant injuries among Alpine or downhill skiers. While improvements in ski boots and bindings since the 1970s have greatly reduced fractures and other injuries below the knee, they appear to have done nothing to protect skiers from serious ACL injuries. According to several studies, the rate of severe knee sprains—which usually involve the ACL—has increased more than threefold since the late 1970s.
Now, researchers who have spent more than two decades studying video tapes of ski injuries have developed an educational